共查询到20条相似文献,搜索用时 250 毫秒
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Liu Z Moore PH Ma H Ackerman CM Ragiba M Yu Q Pearl HM Kim MS Charlton JW Stiles JI Zee FT Paterson AH Ming R 《Nature》2004,427(6972):348-352
Many diverse systems for sex determination have evolved in plants and animals. One involves physically distinct (heteromorphic) sex chromosomes (X and Y, or Z and W) that are homozygous in one sex (usually female) and heterozygous in the other (usually male). Sex chromosome evolution is thought to involve suppression of recombination around the sex determination genes, rendering permanently heterozygous a chromosomal region that may then accumulate deleterious recessive mutations by Muller's ratchet, and fix deleterious mutations by hitchhiking as nearby favourable mutations are selected on the Y chromosome. Over time, these processes may cause the Y chromosome to degenerate and to diverge from the X chromosome over much of its length; for example, only 5% of the human Y chromosome still shows X-Y recombination. Here we show that papaya contains a primitive Y chromosome, with a male-specific region that accounts for only about 10% of the chromosome but has undergone severe recombination suppression and DNA sequence degeneration. This finding provides direct evidence for the origin of sex chromosomes from autosomes. 相似文献
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Structural polymorphism in chromosome 17 总被引:3,自引:0,他引:3
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Meiotic chromosome pairing in Triticale 总被引:1,自引:0,他引:1
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棕色田鼠第一对常染色体多态与染色体数目关系的研究 总被引:1,自引:0,他引:1
研究了棕色田鼠 (Microtusmandarinus)三种性别类型个体 (XY ,XX ,XO)的第一对常染色体多态与染色体数目之间关系 .发现第一对常染色体极不稳定 ,存在( 1 )M ,M (一对中部着丝点染色体 ) ;( 2 )M ,T ,T (一条中部着丝点染色体 ) ;( 3)T ,T ,T ,T(无中部着丝点染色体 )三种多态类型 .性别类型相同个体的染色体数目随第一对常染色体类型的不同发生有规律地变化 .认为罗伯逊断裂是引起棕色田鼠第一对常染色体多态及其染色体数目多态的主要原因 相似文献
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The Y chromosome in human spermatozoa 总被引:20,自引:0,他引:20
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Prenatal chromosome analysis 总被引:1,自引:0,他引:1
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Triple chromosome pairing in triploid chickens 总被引:1,自引:0,他引:1
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Sex chromosome abnormalities 总被引:2,自引:0,他引:2
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Change in chromosome number during continuous irradiation 总被引:2,自引:0,他引:2
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Growth of chromosome ends in multiplying trypanosomes 总被引:7,自引:0,他引:7
Some of the genes for the variant surface glycoproteins of trypanosomes are located close to a discontinuity in the DNA, presumably a chromosome end. We show here that DNA fragments containing these telomeres increase in length in multiplying trypanosomes at a rate of about 10 base pairs per division. We argue that chromosome growth may not be restricted to trypanosomes and could explain the heterogeneity of telomeric DNA fragments observed in some other organisms. 相似文献
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Selection against chromosome aberrations in human lymphocytes 总被引:4,自引:0,他引:4
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Synchrony of chromosome duplication 总被引:1,自引:0,他引:1
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通过引入染色体端粒的概念, 建立了一维元胞自动机中染色体端粒的具有齐次性动力学演化方程, 进一步给出染色体长度以及染色体长度变化率的动力学方程. 相似文献
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